The composite photocatalysts phosphomolybdic acid/titanium dioxide (PMo12/TiO2) applied for industrial wastewater degradation are prepared by sol-gel method and hydrothermal synthesis method . The composites are characterized by infrared spectrometer (IR), X-ray diffraction (XRD)，X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The photocatalytic degradation of 2-buteny-4,6-dinitrophenol (DNBP) is investigated under ultraviolet light irradiation. The effects of the initial pH value, the amount and the reused times of catalyst on degradation of DNBP wastewater are also investigated. The results indicate that the photocatalytic activity of PMo12/TiO2 is significantly better than pure TiO2 photocatalyst when the illumination time is 5 hours, the pH value is 5.10 and the amount of catalyst is 1.00g/L. The degradation rate of the composite catalyst is 98.36%, the COD removal rate is 53.18%. After 3 times repeated use, the PMo12/TiO2 composite photocatalyst still has high activity.